add buckler_flask.py

buckler_flask.py

@@ -0,0 +1,107 @@
+#!/usr/bin/env python3
+"""
+Session interface middlewares to integrate the flask app with Buckler.
+"""
+import json
+import urllib.parse
+import urllib.request
+from datetime import datetime
+
+from flask.sessions import SessionInterface, SessionMixin
+from flask import session, redirect, request
+
+import config
+
+class BucklerSessionInterface(SessionInterface):
+	"""
+	Queries the Buckler server for session data to the current user and
+	application.
+	"""
+
+	def __init__(self):
+		self.url = config.buckler['url']
+		self.app_id = config.buckler['app_id']
+		self.app_key = config.buckler['app_key']
+	
+	def open_session(self, app, request):
+		"""Called when a request is initiated."""
+		user_id = request.cookies.get('userid')
+		user_sid = request.cookies.get('session')
+
+		params = {
+			'app_id': self.app_id,
+			'app_key': self.app_key,
+			'userid': user_id,
+			'session': user_sid
+		}
+		params = urllib.parse.urlencode(params)
+		req = urllib.request.Request(self.url + f"/get_session?{params}")
+		res = urllib.request.urlopen(req)
+		data = json.loads(res.read())
+		if data.get('error'):
+			return None
+		session = BucklerSession()
+		session.update(data['session_data'])
+		session.meta = data['meta']
+		session.cookies = request.cookies
+		return session
+
+	def save_session(self, app, session, response):
+		"""Called at the end of a request."""
+		if not session.modified:
+			return
+		user_id = session.meta.get('user_id')
+		user_sid = session.meta.get('user_sid')
+
+		params = {
+			'app_id': self.app_id,
+			'app_key': self.app_key,
+			'userid': user_id,
+			'session': user_sid
+		}
+		params = urllib.parse.urlencode(params)
+		data = json.dumps(session)
+		req = urllib.request.Request(
+			self.url + f"/set_session?{params}",
+			data=data.encode('utf8'),
+			method='POST')
+		res = urllib.request.urlopen(req)
+
+		last_used = datetime.fromisoformat(session.meta['last_used'])
+		now = datetime.now(last_used.tzinfo)
+		delta = now - last_used
+		if delta.seconds > 600:
+			response.set_cookie(
+				'userid',
+				session.cookies['userid'],
+				max_age=30*24*60*60,
+				secure=True,
+				httponly=True)
+			response.set_cookie(
+				'session',
+				session.cookies['session'],
+				max_age=30*24*60*60,
+				secure=True,
+				httponly=True)
+
+
+class BucklerSession(dict, SessionMixin):
+	"""A server side session class based on the Buckler security shield."""
+	def __init__(self):
+		super().__init__()
+		self.modified = False
+	
+	def __setitem__(self, key, value):
+		super().__setitem__(key, value)
+		self.modified = True
+
+
+def require_auth():
+	"""
+	Requires the user to be properly authenticated with Buckler before
+	accessing any views on the application.
+	"""
+	if not hasattr(session, 'meta'):
+		resp = redirect(config.buckler['login_url'])
+		resp.set_cookie('redirect', request.url)
+		return resp